I have done some looking around, and found the following information that may be of benefit, remembering there are no hard and fast rules but it is a starting point.
Many experts seem to agree and accept that the optimum length of a meeting is 45 minutes.
- We humans seem to focus best in 45-minute increments (bit like Classroom sessions).
- The highest concentration focus in humans lasts 20-minutes; hence you often see the use of a coffee/oblation break used in the middle of the meeting (to stretch legs and refresh etc) giving you 2 x 20 minute blocks in any 45 minute scheduled meeting.
- If the meeting must last longer, split it into 45-minute periods separated by substantial breaks.
- Oddly enough, it also represents about one-half a human REM sleep cycle, which may explain a few things
There also seems a consensus that the best day and time for meetings is considered to be Tuesday Afternoons.
- Not only has everyone had time to recover from the weekend, few people have started the downhill productivity slide toward Friday.
- The later hour encourages attendees to handle their business efficiently so they can go home on time.
- Late afternoons may also work better for customers, since they have fewer conflicts.
Just a note: Remember, people with young children may have to leave earlier than most.
Frequency is a more illusive one to pin down but I think, let yourself be guided by the Purpose of the Meeting and the nature of your business. Operational aspects will require more frequent course alterations/corrections etc, in response to the daily needs, outputs, and delivery so making these maybe a weekly occurrence initially, is a good starting point. Interestingly many Trades start their day with a team site meeting, which might be a good indicator too. Governance is a different beast altogether and as a new Holacracy company, will require a much more frequent schedule as opposed to a more veteran company. This one will depend largely on what the load and time frame of alignment to adoption of Holacracy will be initially, then should taper of into a more rhythmic natural cycle for your company.